1. Field of the Invention
The present invention relates to a display device including a display panel and a parallax barrier in combination and is capable of displaying different images towards a plurality of display directions, respectively.
2. Description of the Related Art
Display devices displaying different images towards a plurality of viewpoints have been proposed as 3D display devices in which an image generation unit and a viewing angle control unit such as a parallax barrier are used in combination. With these 3D display devices, as illustrated in FIG. 6, a certain viewing angle is provided by viewing angle control units 102 arranged outside image generation unit 101. The viewing angle control units 102 are provided for the right-eye image and left-eye image generated by image generation unit 101. Thus, as illustrated in FIG. 7, if the display is viewed from a certain observation area, only the images corresponding to each eye is visually perceived, and a 3D image is recognized by the observer.
Also, by combining the image generation unit and the viewing angle control unit, the use of the display device being able to display different images towards a plurality of viewpoints is not limited to such 3D displays. For example, it is also applicable for use in displays that display different images towards a plurality of observers (hereafter referred as multiple-image display). In other words, with 3D displays, as illustrated in FIG. 8A, the right-eye image and the left-eye image separated by the viewing angle, is observed by the observer's right-eye and left-eye, respectively. On the other hand, with multiple-image display, as illustrated in FIG. 8B, a first image and a second image separated by the viewing angle are observed by different observers, respectively.
FIG. 9 is a schematic cross sectional view illustrating an example of a display device in which an image generation unit and a viewing angle control unit are combined. The display device described in this diagram includes a display panel 110, a parallax barrier 120, a backlight 130, and polarizers 141 and 142. FIG. 9 illustrates a structure using a transmissive type liquid crystal display panel as a display panel 110.
The backlight 130, as described in FIG. 9, includes a light source 131 and a reflection plate 132, and by reflecting the light irradiated from a light source 131 with a reflection plate 132, light is irradiated towards a display panel 110.
The display panel 110 is an active-matrix type liquid crystal display panel, including a liquid crystal layer 113 sandwiched between two glass substrates 111 and 112 facing each other.
The pixels each, as described in FIG. 9, are arranged parallel to the extending direction of the data signal lines (not illustrated), with pixel column L for the left-side image display (image display towards the left side of the display device) and pixel column R for the right-side image display (image display towards the right side of the display device) arranged alternately.
Also, on the surfaces of the glass substrates 111 and 112, which face each other, an alignment film (not illustrated) is provided. The alignment film has been subjected to an alignment process in directions orthogonal to each other at right angles. Each alignment film has been rubbed in each direction parallel to the surface of the substrate. The polarizer 141 is provided on the side of the glass substrate 111 that faces the backlight 130. The polarizer 142 is provided on a displaying side of the parallax barrier 120 which is opposite to the side thereof which is opposite to (backlight 130).
The parallax barrier 120 includes a barrier glass 121 and a light-shielding layer 122. The light-shielding layer 122 is irradiated by the backlight 130, and by blocking a portion of the light transmitted through display panel 110, the light-shielding layer 122 is specific to the display images.
Also, the parallax barrier 120 and display panel 110 are bonded with a resin layer 151 with a certain space therebetween.
However, the conventional structure has a problem in that after the bonding of parallax barrier 120 and display panel 110, peeling of the parallax barrier 120 readily occurs. The explanation of the problem is as follows.
Firstly, the parallax barrier 120 is generally smaller in size than a bonding substrate of the display panel 110 to which the parallax barrier 120 is bonded, so that the parallax barrier 120 can be bonded together with the display panel 110 without protruding from an outer edge of the display panel 110 (in order to prevent hooking and cracks).
Also, a barrier pattern in parallax barrier 120 is required to be larger than or about the same size (area) as a display area of liquid crystal panel 110 (the area where pixels will be displayed). Therefore, with the conventional parallax barrier 120, the barrier pattern is fully formed over the whole parallax barrier 120.
However, in the conventional display device including the parallax barrier 120 and display panel 110 bonded together, as described in FIG. 10, peeling of parallax barrier 120 at the edge portions of the bonding surface occur. The reasons for this can be surmised as follows.
Firstly, the strength is different between the parallax barrier 120 with one substrate and the display panel 110 with two substrates bonded together. Furthermore, the parallax barrier 120 and display panel 110 are bonded by using resin layer 151 including an ultraviolet curing resin, and the resin layer 151 hardens by being irradiated by ultraviolet rays from above the parallax barrier 120. At this time, there is a portion in the resin layer 151 where ultraviolet rays inadequately irradiate due to the light-shielding layer 122 in the parallax barrier 120, and in this portion, resin layer 151 does not harden adequately and a lack in adhesion occurs.
After bonding the parallax barrier 120 and display panel 110, external influences such as heat cause strain due to the difference in thermal contraction rate between materials. If this strain is great, peeling occurs in the weakest portion of the bonding surface, in other words the edge portions of the bonding portions.
For example, if the polarizer 142 bonded with the parallax barrier 120 contracts, the barrier substrate 121 is pulled, thereby generating a warp at the edge portion of this barrier substrate 121. At this time, since the display panel 110 including two substrates bonded together has a certain strength, the display panel 110 is unlikely to be warped, but the adhesive layer 151 being the interface between the parallax barrier 120 and display panel 110 peels off.